scholarly journals Spectroscopic properties of radio-loud and radio-quiet quasars

2019 ◽  
Vol 15 (S356) ◽  
pp. 72-76
Author(s):  
Avinanda Chakraborty ◽  
Anirban Bhattacharjee

AbstractSurveys have shown radio-loud (RL) quasars constitute 10%-15% of the total quasar population and rest are radio-quiet (RQ). However, it is unknown if this radio-loud fraction (RLF) remains consistent among different parameter spaces. This study shows that RLF increases for increasing full width half maximum (FWHM) velocity of the Hβ broad emission line (z < 0.75). To analyse the reason, we compared bolometric luminosity of RL and RQ quasars sample which have FWHM of Hβ broad emission line greater than 15000km/s (High Broad Line or HBL) with which have FWHM of Hβ emission line less than 2500km/s (Low Broad Line or LBL). From the distributions we can conclude for the HBL, RQ and RL quasars are peaking separately and RL quasars are having higher values whereas for the LBL the peaks are almost indistinguishable. We predicted selection effects could be the possible reason but to conclude anything more analysis is needed. Then we compared our result with Wills & Brotherton (1995) and have shown that some objects from our sample do not follow the pattern of the logR vs FWHM plot where R is the ratio of 5 GHz radio core flux density with the extended radio lobe flux density.

1997 ◽  
Vol 159 ◽  
pp. 197-198
Author(s):  
Giovanna M. Stirpe ◽  
Andrew Robinson ◽  
David J. Axon

AbstractWe present preliminary results from a study of broad-line profiles in active galaxies. A simple model in which the emissivity is a broken power-law function of radius, and the BLR clouds emit anisotropically, yields very good fits to almost all the Ha profiles in our data base.


1984 ◽  
Vol 110 ◽  
pp. 237-238
Author(s):  
Peter Barthel ◽  
Colin Norman ◽  
George Miley

In recent years an elegant hypothesis for a unified scheme for compact and extended radio sources, and also radio quiet QSOs and radio loud Quasars has been developed (Scheuer & Readhead 1979, Orr & Brown 1982). In this scheme the relative orientation of (relativistic) beam and observer is thought to explain the observed source morphology. We feel that observations suggest examining compact and extended radio sources from still another “angle”.


Galaxies ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 74
Author(s):  
Avinanda Chakraborty ◽  
Anirban Bhattacharjee ◽  
Suchetana Chatterjee

We perform an analysis of the properties of radio-loud (RL) and radio-quiet (RQ) quasars with MgII broad emission line (i-band magnitude ≤19.1 and z ≤1.9), selected from the parent sample of SDSS DR7 catalogue. For sources with full-width half maxima (FWHM) greater than 15,000 km s−1 (very broad line sample; VBL) we find the radio loud fraction (RLF) to be about 40%. To further investigate this result we compare the bolometric luminosity, optical continuum luminosity, black hole (BH) mass and Eddington ratios of our VBL sample of RL and RQ quasars. Our analysis shows that in our VBL sample space, RL quasars have higher luminosities and BH mass than RQ quasars. The similarity in the distribution of their covering fraction (CF) shows that there is no difference in dust distribution between VBL RL and RQ quasars and hence dust is not affecting our results. We also find that there is no correlation of RL quasar properties with optical continuum luminosity and BH mass.


2009 ◽  
Vol 53 (7-10) ◽  
pp. 121-127 ◽  
Author(s):  
E. Bon ◽  
N. Gavrilović ◽  
G. La Mura ◽  
L.Č. Popović

1996 ◽  
Vol 173 ◽  
pp. 241-246
Author(s):  
Geraint F. Lewis ◽  
Mike J. Irwin ◽  
Paul C. Hewett

The degree of microlensing induced amplification is dependent upon the size of a source. As quasar spectra consist of the sum of emission from different regions this scale dependent amplification can produce spectral differences between the images of a macrolensed quasar. This paper presents the first direct spectroscopic evidence for this effect, providing a limit on the scale of the continuum and the broad line emission regions at the center of a source quasar (2237+0305). Lack of centroid and profile differences in the emission lines indicate that substructure in the broad emission line region is > 0.05 parsecs.


1997 ◽  
Vol 159 ◽  
pp. 260-261
Author(s):  
Michael R. Corbin ◽  
Todd A. Boroson

AbstractComparison of the emission-line and continuum parameters of 48 low-redshift QSOs reveals the asymmetry of the C IV λ1549 broad emission line to be strongly correlated with ultraviolet continuum luminosity, such that increasing luminosity produces increasing redward asymmetry. A similar correlation has been found for broad Hβ. Redward profile asymmetries can be modeled as the result of the gravitational redshift of line photons from the very broad-line region (VBLR) by 109–1010M⊙ black holes, but blueward profile asymmetries require a competing effect such as electron scattering.


1994 ◽  
Vol 93 ◽  
pp. 73 ◽  
Author(s):  
Edward I. Rosenblatt ◽  
Matthew A. Malkan ◽  
Wallace L. W. Sargent ◽  
Anthony C. S. Readhead

2011 ◽  
Vol 20 (3) ◽  
Author(s):  
W. Kollatschny ◽  
M. Zetzl

AbstractBroad emission line regions in AGN are connected with the outer layers of accretion disks. This has been shown by means of line variability studies of individual AGN as well as line profile studies of AGN samples. We could model the broad-line profiles in AGN in a simple way only through rotational broadening of Lorentzian profiles. To individual emission lines belongs one typical Lorentz profile only with a fixed turbulence velocity: e.g., 500 km/s for Hβ, 3000 km/s for CIV λ1550. The rotation velocities in the broad line regions of the AGN range from 1000 to 7000 km/s.


2012 ◽  
Vol 372 ◽  
pp. 012069
Author(s):  
Andrea J Ruff ◽  
David J E Floyd ◽  
Kirk T Korista ◽  
Rachel L Webster ◽  
Ryan L Porter ◽  
...  

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